What were the major developments in military technology from 1939-1945?

Most of the weapons that were truly important in WWII had
already been invented by 1939.  However, there were some major developments in military
technology during the war.

The most important of these
developments, for the war and for the future world, was the development of the atomic
bomb.  The atomic bombs brought an end to the war without an invasion of
Japan.

Another very important development (though it did
not affect the war) was the German development of jet airplanes.  The Germans did not
perfect them in time to make enough to matter, but this technology became hugely
important after the war.

Finally, there were developments
by the Germans in rocket technology.  The V-2 rockets launched at England were the first
long range ballistic missiles in the world.  This invention helped give rise to the
ballistic nuclear missiles we have today (as well as to rockets used for peaceful
purposes).